1. Field of the Invention
The present invention relates to optical scanners and, more particularly, to a scanner mechanism adapted for transmissive scanning and having a light transmitting channel to transfer light from the light source, typically a fluorescent tube placed along the edge of the platen on either side, of the scanner and to direct that light transmitted up through the platen and then over and around the object to be scanned and then reflected down to thereby provide for enhanced light over the entire area of the scanning platform and through the object to be transmissively scanned.
2. Description of the Related Art
Optical scanners are typically used to electronically reproduce visually perceptible images on materials, such as documents, photographs and transparencies, in a digital format for use by a computer. Once images have been stored on a computer, they may be altered and reproduced for any purpose, including the reproduction of high definition imaging for use in multimedia-type applications.
Optical scanners are available in a variety of configurations, tailored to the needs of the user. For example, a conventional flatbed scanner includes a light-receiving device mounted in a light-receiving seat. The seat is coupled to a pair of rails and is movably adjusted along the rails for scanning line-by-line documents and photographs for reflective scanning, and transparencies for transmissive scanning. The light-receiving device includes mirrors and a lens for focusing the image upon an elector-optical transducer, i.e., a charge coupled device (CCD) which then converts the light images into electrical signals. These signals are then digitized for use by a computer for reproduction and manipulation of the digitized image by commercially available software. In conventional scanners, the CCD is centrally mounted within the light-receiving device. The device may also include the use of a focusing mechanism for adjusting the distance between the lens and the CCD.
The light source or sources for conventional scanners, in particular, transmissive scanners, are usually fluorescent tubes placed so that light radiating outward from the tubes is transmitted through the transparency, through an optical pathway and eventually to the CCD. One problem with such scanners is associated with the uneven distribution of light from the light source over the entire area to be scanned. For example, the areas of the transparency closest to the light source will have greater intensity and the areas of the transparency farther away from the light source will have less light intensity. Inasmuch as the intensity of light varies as the inverse of the square of the distance from the light source, it is apparent that a wide range of intensities may result over the entire surface area of the transparency, depending on its size and distance from the light source and whether the scanner includes components to diffuse the light over the entire surface of the transparency.
The primary object of the present invention is to provide a channel-shaped light transmission feature for transmissive scanning in an optical scanner, whereby light radiating from a light source is transmitted from a region adjacent to the light source to an area on one side of the object to be scanned, and is dispersed relatively evenly over the entire area of the object to be transmissively scanned, whereby more efficient use of the light emitting from the light source, and enhanced scanning of the object to be scanned results.
The present invention is directed to a mechanism and method for scanning transparencies within a conventional scanner adapted for transmissive scanning and using a conventional CCD-type image processing structure and capability. The mechanism includes a U-shaped channel which is incorporated within the cover or lid of a flatbed scanner and has its legs extending longitudinally along the outer edges of the platen of the scanner, and above fluorescent tubes positioned under the platen and along the longitudinal axis of the flatbed scanner. The inverted, U-shaped channel includes a reflective layer positioned adjacent the floor of a cavity formed in the scanner lid, a fiber optic light conduit for transmitting light upward from the legs and through the center, or base part of the U-shaped channel, and a collimating layer positioned adjacent the conduit layer on one side, and adjacent the platen of the scanner on the other side, for collimating light which has been transmitted through the polymeric conduit and reflected from the reflective surface to thereby direct the light through the object to be scanned and through an optical pathway to the CCD of the scanner.
The preferred light diverting channel of the present invention includes a polymeric conduit to serve as a wave guide, a reflective surface, and a collimating layer which includes a sheet having wedge-shaped collimators on one side and arcuate truncated edged lenses on its opposite side. With incorporation of the light directing channel of the present invention, the transmissive scanning is improved by virtue of more efficient transfer of light from the light source to and through the object to be scanned, and, also, more even distribution of light over the entire area of the object to be scanned.